This invention relates generally to the field of medical ventilators, and more particularly to a ventilator having a manifold on which the pneumatic components of the ventilator are mounted.
Medical ventilators have been developed to provide artificial respiration to patients whose breathing ability is impaired. Typically, a ventilator will deliver a breath to the patient from a pressurized source of gas. A gas storage chamber, called an accumulator, is usually provided on the ventilator to store a supply of gas for use when the demand by the patient exceeds the flow rate of the source. Pressurized gas flowing from the accumulator is brought down to a lower, constant pressure level by a regulator. Flow to the patient during inspiration is governed by a flow control valve, which is downstream of the regulator. When the flow control valve opens, pressurized gas is introduced to the patient's lungs. After the flow control valve closes, ending the inspiration phase of the breath, the patient's respiratory gases are vented to the atmosphere through an exhalation valve, which opens after respiration is completed and closes before the next inspiration phase begins.
Previous ventilators have had microcomputer controllers to enable the ventilator to operate in several modes so that the degree of support that the ventilator provides to the patient's natural breathing patterns can be varied. At one extreme, the ventilator can provide fully controlled ventilation in which the ventilator has complete control over when the breath is delivered and the volume of gases received by teh patient during each breath. In the fully controlled mode, all of the flow parameters are preset by an operator in accordance with the particular needs of the patient.
At the other extreme, the ventilator can be programmed to permit "spontaneous" breathing by the patient. During the spontaneous breathing mode, the breath rate, the volume of gas inhaled during each breath, and other flow parameters are not predetermined. The inspiration and expiration phases of each breath are commenced in response to efforts by the patient. In between the "volume control" and the "spontaneous breath" modes, various degrees of ventilator supported respiration are available.
To promote the portability of the ventilator, all of the pneumatic and electrical components of the ventilator must be mounted on a stable base, which is typically formed by a sheet metal chassis. The components are secured to the chassis by means of separate mounting brackets. To establish fluid communication between the various pneumatic components, previous ventilators have utilized flexible tubing which is manually joined to the respective inlets and outlets of the components.
A major drawback to previous ventilators of this type has been that due to the large quantities of tubing required to interconnect the various components, a complex arrangement of intertwined tubing is created. As a result, the ventilator is difficult to assemble and service. Additionally, in order to have sufficient access to mount the components on the base with the brackets, and to connect the tubing, the overall size of the ventilator is quite large. Consequently, the ventilator occupies a large amount of the scarce space surrounding a hospital bed in an intensive care unit.
Thus, a need exists for a ventilator which mounts the components and establishes fluid communication between the components in a manner which enables the ventilator to be compact, inexpensive, and easy to assemble and repair.